In clinical practice, we often encounter maternal infectious diseases that require antibiotics. Many young clinicians are at a loss at this point, not knowing which anti-infective drugs to use and which not to use. That’s why Medical Voices is talking about this issue today, in the hope that it will be helpful. To understand this section, it is important to be familiar with the FDA’s classification criteria for maternal medications. FDA grading standards on drugs in pregnancy: The FDA classifies drugs into 5 levels of harm to the fetus, A, B, C, D, and X, based on their teratogenicity to the fetus. Highlights Class A: Proven to be non-hazardous to the fetus in studies with controlled groups in humans. This includes multivitamins, pregnancy vitamin preparations, but not high-dose vitamin preparations. Class B: proven harmless to fetuses in animal studies, but no studies in humans yet; or proven adverse effects in animal studies, but this effect was not found in studies with good control groups in humans. Class C: There are no good animal tests or studies in humans yet, or there are adverse effects on the fetus in animal tests, but there is a lack of available information in humans yet. Many drugs commonly used during pregnancy fall into this category. Category D: There is evidence of harm to the fetus, but the pros and cons should be weighed during pregnancy and can still be used when the benefits outweigh the harms. For example, phenytoinamide, carbamazepine, etc. Class X: The risks to the fetus have been shown to significantly outweigh any benefits. For example, isotretinoin for acne can cause a variety of malformations in the fetal central nervous system, face and cardiovascular. I. Antiviral drugs ① Ribavirin (virazole): that is, triazolyl nucleoside, a class X drug, animal experiments found that almost all kinds of test animals after the application of this product, teratogenic and embryonic killing effect, pregnancy is prohibited. The elimination of this product in the body is very slow, and can not be completely removed from the body four weeks after stopping the drug. ②Acyclic guanosine: Acyclovir, a class B drug. It inhibits DNA synthesis and is used for herpes virus infections; Vanelovi: Class B; Ganciclovir: Class C. ③Interferon: best not used during pregnancy. ④Lamivudine and zidovudine: Class C. They can be used for AIDS treatment during pregnancy. II. Anti-tuberculosis drugs ① Isoniazid: It is a class C drug. This drug has high lipid solubility, low molecular weight and almost no binding to plasma proteins, so it can easily pass through the placenta and the concentration in the umbilical cord blood is higher than that in the mother’s blood. However, a retrospective analysis of 4900 pregnant women using isoniazid showed no increase in the rate of fetal malformation, and it is now considered to be available for pregnant women with TB. ②Rifampicin: Class C drug. Animal studies have found that spina bifida and cleft palate can occur in fetuses when RFP is applied to pregnant rats and mice. However, in 204 patients who used Rifampicin during pregnancy, the rate of neonatal malformation was not increased. It is a cautionary use during pregnancy. However, the drug concentration in breast milk is low, so it can be used during lactation. (3) Ethambutol: Class B drug. At present, it is believed that this product has no teratogenic effect on human and is preferred in case of tuberculosis during pregnancy. ③Antifungal drugs ①Mycetin and clotrimazole, both are class B drugs, available during pregnancy; ②Miconazole and fluconazole are class C drugs; ③Dimycin B is used to treat systemic mycobacterial infections, no reports of increased congenital malformations; ④Itraconazole (C) lacks research in early human pregnancy, use with caution during pregnancy; ⑤High dose fluconazole can cause fetal malformations in animals, but no reports of human pregnancy teratogenic. Antibiotics ① Penicillin: It is a class B drug with low toxicity and is the safest anti-infective drug for pregnant women, including broad-spectrum penicillin such as ampicillin, piperacillin, melocillin and other β-lactam preparations. ②Cephalosporins: Class B drugs. These drugs can pass through the placenta, but there are no reports of teratogenicity of such drugs, and the plasma half-life is shorter in pregnancy than in non-pregnancy. They are available during pregnancy. (3) Aminoglycosides: They are class D or C drugs. These drugs are easy to pass through the placenta, and the drug concentration in the umbilical cord blood increases significantly, which is harmful to the pregnant woman and the fetus, and is prohibited or used with caution during pregnancy. ④Macrolides: Most of them are class B. They are not easy to pass through the placenta because of their large molecular weight. It can be used for penicillin allergy and chlamydia and mycoplasma infection. ⑤ Tetracyclines: mostly class D, including tetracycline (D), hygromycin (D), doxycycline (D), methomycin (D), etc. Such drugs are easily passed through the placenta and into breast milk, and are teratogenic. Tetracycline fluorescent substances can be deposited in tooth enamel and fetal bone, affecting fetal tooth enamel and physical development, leading to intrauterine growth retardation. When a pregnant woman has renal insufficiency, it can cause acute fatty liver in pregnant women and is prohibited during pregnancy. The concentration of these drugs in breast milk is high, and breastfeeding needs to be weighed against the advantages and disadvantages of using or suspending breastfeeding. (6) Chloramphenicol: It can pass through the placenta and enter the breast milk, has a suppressive effect on the bone marrow, and can cause “gray baby syndrome” when used in premature babies. It is prohibited during pregnancy and lactation. (7) Quinolones: Most of them are Class C drugs, including pyrazole, haloperidol, ciprofloxacin, ofloxacin, sparfloxacin, etc. The mechanism of action of these drugs is to inhibit bacterial DNA. The mechanism of action of such drugs is to inhibit bacterial DNA helicase, such drugs have a strong affinity for bone and cartilage, which can cause irreversible arthropathy in animals, or affect fetal cartilage development, prohibited during pregnancy. ⑧ sulfonamides: mostly C class, this class of drugs easily through the placenta, animal experiments have teratogenic effects, but no human reports. Application in late pregnancy can cause thrombocytopenia and hemolytic anemia in newborns. It also competitively inhibits the binding of bilirubin to albumin, causing neonatal hyperbilirubinemia. Use with caution during pregnancy and forbidden before delivery. ⑨Jessamycin: including jessamycin, clindamycin, etc., is a class B drug. It can pass through the placenta and enter the breast milk, no record of adverse effects on the embryo, relatively safe. ⑩Metronidazole: Now it is class B, and it was classified as class C in the past. It has been reported that 1700 cases of early pregnancy did not increase the rate of malformation after application, and recently the FDA has classified it as a Class B drug. The CDC has recommended it for the treatment of vaginal trichomoniasis during pregnancy. However, tinidazole is a class C drug and should be used with caution during pregnancy. Ornidazole: No teratogenicity in animal studies, but no controlled studies in pregnant women, use with caution.